Kalla, a cardiac researcher, says the study reviewed health records from 1,000 hospitals covering patients between the ages of 18 to 55 years old.

Those who used marijuana had a 26 percent increased risk of having a stroke and a 10 percent higher risk of heart failure.

Pot appears to directly impact the heart.

“When cannabis affects human heart cells those cells are less able to squeeze and therefore the heart as a whole is not able to pump as well,” said Dr. Kalla. ”

The study was conducted from 2009 to 2010 before cannabis was legal in most states.

Researchers did not account for quantity or frequency of pot use or whether or not it was ingested or smoked.

So doctors say more research is needed but the risks should be considered.

“As cannabis becomes legalized across the country I think both the medical and general community will need to become more aware of potential cardiovascular complications that can arise from cannabis use,” says Dr. Kalla.

Previous studies have shown that heavy cannabis use can cause psychiatric and respiratory problems and can impair learning, memory and attention.